妊娠肉牛营养需要的研究

NUTRIENT REQUIREMENTS OF BEEF COWS IN THE LAST HALF OF PREGNANCY

为了研究肉用母牛妊娠后半期的营养需要,1984～1989年利用4～8岁经产改良母牛66头次,进行了3期共6个不同营养水平组的常规饲养试验,测定妊娠72天至分娩的妊娠营养需要量,每30天为一段。最高营养组较NRC标准高15％,最低营养组则略高于目前山西国营肉牛场和农村采用的水平。所取得的数据证明本试验营养水平基本满足妊娠后期母牛的需要。在这种情况下,分娩时胎重(W_1是用分娩前后体重之差求得),为犊牛初生重(W_2)的1.58倍;犊牛初生重与妊娠母牛的营养水平关系不大(P>0.2),而与母牛的体重(W)呈高度的正相关(W_2=10.88+0.0492W,P<0.001)。以t代表妊娠天数,则妊娠后半期胎日增重(G_D)为:G_D(kg)=(0.00879t-0.08545)(0.1017+4.6^(-4)·W)妊娠后半期每千克胎增重所需能量(不包括母牛的维持能量需要0.3222W^(0.75)NEmMJ)NEg或NEm均与妊娠天数呈明显的正相关(α<0.05,n=168),平均ME用于沉积胎能的效率为13％。NEg(MJ)/G_D(kg)=0.10008t-6.10948或NEm(MJ)/G_D(k=0.19188t-10.59054从试验获得的226组数据可知妊娠母牛干物质采食量(DMI)与母牛体重及妊娠天数均呈极高的正相关(P<0.001)。DMI(kg)=4.762+4.918^(-3)·W+7.229^(-3)

In order to study the nutrient requirements in the last half of pregnancy of beef cows, 3 feeding trials of 6 different nutrient levels were conducted from 1984 to 1989 with 66 head-time pluriparous crossbreeding cows of 4~8 years of age. Determinations of the requirements were made for each 30 days as a period from 72 days of pregnancy to parturition. The high nutrient level group was 15% higher than the NRC standards. The low level group was slightly above the level of state farms of beef cattle and rural cattle in Shanxi. The results showed the nutrient levels in the experiments could basically satisfy the requirements of the cows at the last half of pregnancy. The birth weight of calves and the nutrient level of pregnant cows were not correlated (P>0.2) but the correlation between the calf birth weight and the body weight (W) of pregnant cows was highly significant (P<0.001). Birth weight of calves = 10. 88 + 0.0492W The conceptus weight was 1.58 times higher than birth weight. The following equation was used to estimate the conceptus daily gain. Conceptus daily gain (kg) = (0.00879t - 0.08545) (0. 1017 + 4. 6-4W) In the last half of pregnancy the NEg or NEm requirements per kg conceptus weight showed positive and significant corelation with the days of pregnancy (α<0.05, n = 168). The efficiency of ME used to deposit fetal energy was 13%. NEg(MJ)/kg conceptus gain = 0. 10008t - 6. 10948 or NEm(MJ)/kg conceptus gain = 0. 19188t - 10.59054 From 266 data of experiments the correlation coefficient between DM intake of pregnant cows and their body weight was extremely significant (P<0.001). DMI=4.762+4.918-3w+7.229-3t In the above regression equations W = body weight of cows, t = days of pregnancy. With this equation estimation of DM allowances for cows during the last half of pregnancy and addition of NEg or NEm above the maintenance requirement(0.32217W0.75NEm, MJ) may be made. ( exclude maintenance energy requirements of cows)